CHICAGO – The elimination of dumb on-field mistakes is one of the most noticeable differences between the best teams in baseball and the worst.

The Cubs could learn a thing or two from the Pirates, co-owners of the best record after Friday’s 6-2 win at Wrigley Field. The number of boneheaded plays the Cubs (36-48) have committed this season is approaching their win total, and they were at it again against Pittsburgh.

“In baseball, every mistake stands out,” manager Dale Sveum said.

Shortstop Starlin Castro was responsible for the most glaring miscue. With the Cubs trailing by four runs in the eighth inning, Castro, on second after a two-out double, was easily – and embarrassingly – picked off by Pirates catcher Russell Martin, who delivered a laser throw from home. It ended the inning, and the Cubs went down quietly in the ninth.

“It’s not a smart play,” Castro said. “I feel really, really bad. That can’t happen. … I try to be aggressive, but that can’t happen.”

When Sveum was questioned about the play, he was rightly exasperated by Castro’s decision to take such a large lead when he would likely score on a hit. Castro’s mistake was the Cubs’ third avoidable miscue.

Center fielder Dave Sappelt took a terrible route on Neil Walker’s fly ball in the third, resulting in a triple. Walker later scored to give the Pirates the lead.

The Cubs gifted the Pirates (53-32) another run that same inning when catcher Dioner Navarro tried to throw out Garrett Jones on a steal of second as Jose Tabata struck out for the second out. Instead, the throw was off-target and Andrew McCutchen, who was at third base, scored easily, credited with stealing home.

“I think we have what it takes, but unfortunately it hasn’t been working out the way we want it to go,” Navarro said.

In the toughest division in baseball with three teams – the Pirates, Cardinals and Reds – owning three of the best records in the majors, a combined 152-102, the Cubs have no chance at staying competitive if they don’t play better against their NL Central rivals. The Cubs have been awful in the division with an 11-26 record. Their .297 winning percentage is the lowest in the majors by any team against its own division. Yes, even worse than the Marlins and Astros.

“We understand we need to put a solid game together when we play them and bring our A game against those top three teams on the top of our division,” pitcher Jeff Samardzija said. “ … You can’t give them windows of opportunities. They take advantage of them. They don’t give cheap outs. They don’t make mistakes on the base paths so therefore you’ve got to be on the top of your game too.”

The Cubs have given no indication they’re capable of doing that. Samardzija’s struggles getting Pirates starting pitcher Francisco Liriano out highlighted the Cubs’ problems: an RBI single after intentionally walking the No. 8 hitter in the second and a four-pitch walk to start the sixth.

And the Cubs still have 39 games remaining against division opponents. Buckle up.

“If you want to beat these good teams on the top of your division, pitchers can’t get hits, pitchers can’t get walked,” Samardzija said. “Bottom line.”

• Meghan Montemurro covers the White Sox and Cubs for Shaw Media. Write to her at mmontemurro@shawmedia.com. Read the Sox Insider and Inside the Cubs blogs at NWHerald.com and on Twitter @Sox_Insider and @InsideTheCubs.

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